In conventional data communication systems a local node with a large number of SONET/SDH terminations may process a large variety of payload types. Common payloads are Asynchronous Transfer Mode (ATM), Packet Over SONET (POS), and Time Division Multiplexing (TDM) traffic. In general, each of the payload types is processed by specialized hardware residing in disparate cards. For traffic not terminating in the local node, the traffic may be groomed and transported from input fibers to arbitrary output fibers.
The Combus standard provides a common interface between SONET termination devices and payload processing devices. However, the Combus standard is limited to OC-3 streams and contains 11 signals per interface. For a high capacity node, the number of signals required typically exceeds the limits of the Combus standard.
Another existing approach to connecting SONET/SDH termination devices to payload processing devices requires the reconstruction of a serial SONET/SDH stream post SONET/SDH termination. However, this method suffers from the disadvantage of requiring duplicate SONET/SDH processing at the payload processing devices.
It is an object of this invention to provide an improved serial bus interface to connect SONET/SDH termination devices with payload processing devices, across system backplanes.
It is a further object of this invention to provide a bus interface to connect SONET/SDH termination devices with payload processing devices utilizing a minimum number of signals.
It is still a further object of this invention to provide a bus interface that can scale with future advances in bandwidth in serial link technology.
It is a further object of this invention to support multiple SONET/SDH line rates. In particular STS-12 is to be supported at 622.08 Mb/s, STS-48 is to be supported at 2488.32 Mb/s and STS-51 (a custom extension to the SONET/SDH standards) is to be supported at 2643.84 Mb/s.
It is a further object of this invention to support two line coding schemes: 8B/10B encoding of STS-12 at 622.08 Mb/s producing an effective line rate of 777.6 Mb/s, and SONET scrambled coding for all three rates (STS-12, STS-48, and STS-51) with no expansion in effective line rates.
It is a further object of this invention to support two modes of line testing: entire links can be tested by inserting and checking PRBS sequences, and the SPE payload of the largest concatenated STS-Nc which the link can carry (STS-12c, STS-48c, STS-51c) can be individually tested by inserting and checking PRBS sequences.
It is a final object of this invention to support diagnostic line testing by inserting B1 framing errors at the transmitter, to be checked at the receiver.